6533b822fe1ef96bd127ca5b

RESEARCH PRODUCT

Packing technology, column bed structure and chromatographic performance of 1-2-μm non-porous silicas in high-performance liquid chromatography

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This work is aimed at further elucidating the aggregation behaviour of micron- and submicron-size non-porous silicas and the column performance of 1–2-μm C18 silicas in reversed-phase high-performance liquid chromatography of low-molecular weight compounds. It is demonstrated that highly ordered, dense, porous aggregates of such silica beads were obtained by gravity settling and centrifugation. The slurry techniques applied at constant flow-rate and a pressure up to 50 MPa provided less-ordered aggregates, but generated an acceptable performance of columns when 1–2-μm C18 silica beads were employed. To operate columns of 53 mm × 4.6 mm I.D., the maximum flow-rate needs to be ca. 2.5 ml/min at an inlet pressure of 50 MPa. To keep extra-column effects to a minimum, the injection volume should be about 0.6μl, the volume of the detector cell about 0.3μl and the time constant of the detector <50 ms. Such columns enable fast separations of mixtures of low-molecular-weight substances in less than 30 s.